Through-the-obstacle radar systems enable gathering information through obstacles such as walls, doors, ground, smoke, vegetation and other visually obstructing substances and, as such, may be invaluable for Intelligence, Surveillance, and Reconnaissance (ISR) applications, including military, counter-terrorism forces and law enforcement applications.
The problem of effective implementation of through-the-obstacle radar systems for ISR applications has been recognized in prior art and various systems have been developed to provide a solution, for example:
U.S. Pat. No. 6,222,481 (Brusmark et al.) entitled “Method of detecting and classifying objects by means of radar” discloses a method comprising transmitting a broadband radar signal comprising wavelengths that coincide with characteristic lengths of targets to be detected and classified, and receiving a returned echo signal and analyzing the signal in a combined time-frequency domain. The invention comprises determining characteristic frequencies in the signal return and their mutual time relations. A comparison with the corresponding stored values of an analysis of possible targets is performed.
U.S. patent application No. 2001/035,837 (Fulerton et al.) entitled “Time transfer utilizing ultra wideband signals” discloses a system and method for selective intrusion detection using a sparse array of time modulated ultra wideband (TM-UWB) radars. Two or more TM-UWB radars are arranged in a sparse array around the perimeter of a building. Each TM-UWB radar transmits ultra wideband pulses that illuminate the building and the surrounding area. Signal return data is processed to determine, among other things, whether an alarm condition has been triggered. High resolution radar images are formed that give an accurate picture of the inside of the building and the surrounding area. This image is used to detect motion in a highly selective manner and to track moving objects within the building and the surrounding area. Motion can be distinguished based on criteria appropriate to the environment in which the intrusion detection system operates.
U.S. patent application 2003/164,790 (Tsubota et al.) entitled “Detecting system” discloses a position detecting system used to monitor a suspicious person and to give an alarm by using a radar which transmits/receives a microwave or a millimeter wave. As the shape of a detectable area of the radar and that of the area to be monitored are not always equal to each other, an alarm may be erroneously given in response to the object outside the area to be monitored. The area to be monitored is surrounded by a plurality of reflectors, and the coordinate values of the reflectors and the detecting object are calculated based on the signals reflected from the reflectors and the detecting object, and are then compared.
U.S. patent application No. 2004/178,942 (McLemore) entitled “Apparatus and method for rapid detection of objects with time domain impulsive signals” discloses a method and system for detecting objects of interest in a target area using ultra wide band (UWB) RF signals. A transmitter and antenna array generate ultra wide band RF impulsive signals that are used to probe a target area that may include an object of interest. An antenna and a signal processor receive return signals from the target area and process the return signal to generate a set of coordinates. The coordinates of the processed return signals are compared to coordinates of known objects in a pre-existing database to determine whether there is a match between the return signal and a known object. When there is an indication of a match, the existence of the known object is displayed to an operator of the system.
U.S. patent application No. 2005/264,438 (Fulerton et al.) entitled “System and method for spatially diverse radar signal processing” discloses an ultra wideband radar system for detecting moving objects. The system comprises an antenna, which may be scanned in at least one dimension, and a signal processor wherein the signal processor includes a scan combiner that combines scan information in accordance with a candidate trajectory for the moving object. Scans may be combined by integration or filtering. A fast calculation method is described wherein the scans are combined into subsets and subsets are shifted in accordance with the candidate trajectory before further combination.
U.S. patent application 2006/061,504 (Leach et al.) entitled “Through wall detection and tracking system” discloses a system for detecting and tracking an individual or animal, and comprises producing a first return radar signal from the individual or animal with a first low power ultra wideband radar; producing a second return radar signal from the individual or animal with a second low power ultra wideband radar; maintaining the first low power micro-power radar a fixed distance from the second low power ultra wideband radar; and processing the first return radar signal and the second return radar signal in detecting and tracking of the individual or animal.
U.S. patent application 2007/057,761 (Johnson) entitled “Motion detector” discloses various embodiments of a motion-monitoring system comprising at least one antenna fixed within a barrier, the at least one antenna transmitting at least one first radio-frequency signal through the barrier to at least one volume outside the barrier, the at least one first radio-frequency signal reflecting from at least one object in the at least one volume to produce a plurality of second radio-frequency signals, which are received by the at least one antenna, at least one sensing circuit sensing the plurality of second radio-frequency signals and generating a plurality of time-domain output signals, and at least one processor receiving the plurality of time-domain output signals and comparing at least one successive time-domain output signal to at least one previous time-domain output signal to estimate at least one characteristic of the at least one object, including a motion of the at least one object.
International Application No. WO07/047,419 (Zemany) entitled “Motion detection system using CW radar in combination with additional sensors” discloses use of additional one or more sensors with the CW radar to confirm the motion detection result.